People were saved through Paul's message prior to the completion of the scriptures. The Gospel of Grace . Which I have a suspicion you may not know ? Its Paul who is given the revelation by Jesus that s not revealed prior to Paul . So if you are ruling Paul's words your disobeying God just as if they would have done by ignoring moses . God has always used a spokesman. Paul being the primary to the Church .
No, Paul evangelized the Words of Christ. And within that we have clearer meaning. But the Disciples also evangelized and the Gospel by word of mouth was spreading. And when we look at the Gospels, we have 3 Disciples view (Book of Mark was spoken in Aramaic by Peter to his Disciple Mark who wrote the words down in Greek)(Church Father's explain this to us) and we have Luke's version. Those 4 versions are more than enough to be secure in the Gospel of Christ. Thankfully, we have 27 Books in the New Testament and each one broadens our knowledge of God.